[AccessD] SQL Puzzler

I think I have a solution, but first I need to confirm or deny a few ground
rules:

1. Is the Attachment-Type list fixed (i.e. nothing unexpected to be found)?
2. Is every Sales Order guaranteed to have at least one Attachment of a
known type?
3. If the answers to 1 and 2 are Yes, would an output something like this
be acceptable:

Sales Order #        Artwork      Photo      Customer-Service
123                               Y                                        Y
234                                                 Y
345                               Y                Y                      Y

Or, if the answer to question 2 is No, then such row might look like this:

456

Arthur